As is well known, dogs do not have sweat glands except on footpads on their soles, and after exercise or when the air temperature is high as in the summer, dogs open their mouths widely, droop their tongues, and breath in a panting manner mainly to cause water in the oral cavity to evaporate and suppress body temperature rise by a cooling action of the heat of evaporation. However, because such a body temperature regulating mechanism is far inferior in efficiency in comparison to body temperature regulation by sweating as in humans and horses, dogs generally cope less well with heat than they do with cold.
Although for a dog that is weak from heat, frequent replenishment of water is thus necessary at times of high temperature, water in a water drinking container that is placed outdoors warms especially rapidly due to insulation and external air temperature and because such water cannot be drunk even if the dog is thirsty, body temperature regulation fails and leads to debilitation in many cases.
Although conventionally as water drinking containers for dogs, cats, and other animals, a container, arranged to eliminate fallen hair that float on the water surface (Patent Document 1), a container, arranged for placement of a drug for water quality improvement (Patent Documents 1 and 2), etc. have been proposed, the abovementioned problem of water temperature rise is not taken into consideration in these arrangements. Also, although there are devices that electrically cool water for pet animals, these have not become generally popular due to being large in arrangement and expensive.
[Patent Document 1] Japanese Published Unexamined Patent Application No. 2006-333860
[Patent Document 2] Japanese Published Unexamined Patent Application No. 2005-110522.
[Patent Document 3] Japanese Published Unexamined Patent Application No. 2005-295981.